What he said in Spare was no more harmful than anything Prince Charles said in his Dimblebore book;
Don't be daft. Charles never wrote a book anyway. Your 'arguments' are staler than last week's sliced white.
His family don’t have to say any words in public about him because they have a lot of influence and many paid and unpaid lackeys to do that for them; eg allies like Jeremy Clarkson and Piers Morgan, tame royal correspondents, obsequious historians holding out for honours, and current or ex staff who are willing to leak stories at strategic moments, who will be given a job or a grace and favour apartment in return.
Yawn at the 5 year old talking points.
Harry and his wife have shown that they're nothing special (and that's being generous) and the royals have managed fine without them. Harry's just not worthy of all that effort.
As for the twerking; I choose to interpret that as the harmless bit of fun and stress reliever it was rather than judge someone for a bit of dancing that mimicked an on-line trend!
They/she put it out there for the public to judge.
Harry has found freedom to point at his crotch in his wife's twerking videos. Why would he want to come back to 'help' his family if they're that ghastly and if he's happy with his wonderful new life?